1. Field of Invention
The present invention relates to an earphone without impulse noise and conductive hearing loss, wherein the sound waves from the loudspeaker thereof would not directly transmit to the middle ear so as to prevent conductive hearing loss caused by the direct impact of the sound pressure.
2. Description of Related Arts
In 1990, the National Institutes of Health Consensus Development Conference State announced: "there are about 28 million American have hearing loss problem, among those people, at least one million people have hearing loss from high impact noise environment." Additionally, in 1993, National Ear Care Plan claimed that approximate 1.7% of American Teen, under 18, have hearing disability. Furthermore, in 1997, UT Southwestern Medical Center stated: "approximate 20% of American Teen, between 13-19, have hearing disability. The major cause of the hearing loss is people exposed to the noise especially the impulse noise from the earphone." People should concern the control of the sound volume while using the traditional earphone (continuous hearing not more than one hour or six hours per day when sound pressure at 105 dB or 95 dB respectively). In fact, this flash impulse noise contains high sound pressure and may damage the eardrum or middle ear hearing loss. It is called Conductive Hearing Loss. America's medical report recently stated that the percentage of people having the Conductive Hearing Loss is gradually increasing since earphones are improperly used to listen hot music such as Rock and Roll.
Moreover, earphone receives signal from source such as walkman o communicator devices, and transfers the sound wave to human ear which the perceptible frequency range of human being is about 20 Hz to 20 kHz. In fact, the reproductive resonance of sound interval in above frequency range is not ideal since the source of sound is not come from millions dollars of high-end musical devices but from the walkman or communicator devices. Among these signal from walkman or communicator devices exist lots of feedback or noise, so the noise of `beep` sounds often found at high frequency range and `woo` sounds often found at low frequency range.